Jimmy7
Senior Member
- Location
- Boston, MA
- Occupation
- Electrician
I have a question regarding a breaker description. What does AS stand for in the following? 400AS/250AT 480V 80% Rated 100 kA 3 Pole
Breaker Question
- Thread starter Jimmy7
- Start date
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
It means you have anelectronic trip breaker that has a 400A sensor in it that has an amp rating of 250A.
Think of it as the size of the CTs inside the breaker.
Think of it as the size of the CTs inside the breaker.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Yes.
AF is still used, it is the physical size of the breaker frame and often the interior current carrying contacts.
It is very common to find a 600A frame with a 400A sensor set for a 250A trip.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Like AF which means "Amp Frame", AS means "Amp Switch", but is irrespective of the frame size. This is because some mfrs are no longer supporting all of the multiple frame sizes the way they used to, yet although the frames may be the same, the actual switch inside might be different. So for example some mfrs have eliminated their 600A frame size because in their recent designs, the 800AF is smaller than the old 600AF anyway. So they go from a 400A frame to an 800A frame, but in between those, they have a 600A SWITCH mechanism in the 800A frame, which costs less than the 800A switch in the 800A frame. The engineers usually don't really care, but if someone submits a 600A breaker in an 800A frame, it caused needless paperwork. Some have learned this and have stopped using "AF" and changed to using "AS" so as to not cause multiple RFIs and reviews back and forth when the frame size doesn't match their drawings.
This has been triggered because breaker mfrs selling throughout the world have all had to redesign their Molded Case Breakers due to RoHS (Reduction of Hazardous Substance) laws in the EU and elsewhere, making it illegal to use non-recyclable materials. In MCCBs, that was a huge problem because the cases (frames) were all made with FRP (Fiber Reinforced Plastic) which cannot be recycled. Here in North America, RoHS rules have not been adopted (yet), so older designs of MCCBs can still be sold and used DOMESTICALLY, but mfrs cannot ship them, or equipment with them inside, overseas as of July of 2017. So all of the breaker mfrs have released newer designs, often referred to as "World Design" versions that have highly engineered frames to provide the equivalent strength of the old FRP materials. The cost to develop those was very very high, so the old system of frame sizes was all but thrown out in order to reduce the number of required redesigns.
This has been triggered because breaker mfrs selling throughout the world have all had to redesign their Molded Case Breakers due to RoHS (Reduction of Hazardous Substance) laws in the EU and elsewhere, making it illegal to use non-recyclable materials. In MCCBs, that was a huge problem because the cases (frames) were all made with FRP (Fiber Reinforced Plastic) which cannot be recycled. Here in North America, RoHS rules have not been adopted (yet), so older designs of MCCBs can still be sold and used DOMESTICALLY, but mfrs cannot ship them, or equipment with them inside, overseas as of July of 2017. So all of the breaker mfrs have released newer designs, often referred to as "World Design" versions that have highly engineered frames to provide the equivalent strength of the old FRP materials. The cost to develop those was very very high, so the old system of frame sizes was all but thrown out in order to reduce the number of required redesigns.
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